Terra Preta de Indio
Biochar Soil Management
Content: J. Lehmann
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Basic Information | Projects | The Terra Preta Network | Pictures | References
 
Projects on Amazonian Dark Earths
Our project activities have various dimensions and are comprised of efforts to discover the properties, origin and distribution of Amazonian Dark Earths as well as to learn new and exciting aspects of soils in general. Ultimately, we drive towards the goal to apply this knowledge to the development of sustainable soil management and mitigation of environmental degradation (see here for more information). Up to now, we have studied nutrient availability, crop yield, weed dynamics, nutrient leaching, long-term phosphorus dynamics, and carbon cycles in Amazonian Dark Earths. We are specifically interested in the properties and changes of biomass-derived black carbon (bio-char, charcoal) in Amazonian Dark Earths.
 
Nutrient properties and dynamics in Amazonian Dark Earths
Laboratory Experiments, since 2003:
The reasons for the extraordinarily high retention capacity and nutrient availability of Amazonian Dark Earths is explored. Apart from presumably high nutrient additions by Amerindian populations, the observed high nutrient availability is a consequence of the specific properties of biomass-derived black carbon (or bio-char, charcoal) in Amazonian Dark Earths. At identical organic matter contents, bio-char-rich Amazonian Dark Earths have more cation exchange capacity (CEC) than adjacent soils bearing the same mineralogy. Since bio-char consists of very small (mostly less than 50 micrometer) particles, the surface properties of these particles and not their bulk chemistry are key to the effects on CEC. With the help of synchrotron-based X-ray spectroscopy (C (1s) NEXAFS) coupled with microscopy (STXM) both oxidation of the otherwise hydrophobic bio-char surfaces as well as adsorption of non-bio-char organic matter was identified as the source of the CEC. As a consequence, the charge density (potential CEC per unit surface area) was greater in BC-rich Amazonian Dark Earths than adjacent soils. Additionally, a high specific surface area was attributable to the presence of BC, which may additionally contribute to the high CEC found in soils that are rich in BC.

We are also studying the inorganic and organic phosphorus forms of terra preta using sequential fractionation and P XANES to investigate the forms of inorganic P and its changes over long periods of time.

Publications:
Lehmann J, Campos CV, Macedo JLV and German L 2004 Sequential fractionation and sources of P in Amazonian Dark Earths. In: Glaser B and Woods WI (eds.) Amazonian Dark Earths: Explorations in Time and Space, Springer, Berlin, Germany. pp. 113-123.
Lehmann J, Liang B, Solomon D, Lerotic M, Luizão F, Kinyangi F, Schäfer T, Wirick S, and Jacobsen C 2005 Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy for mapping nano-scale distribution of organic carbon forms in soil: application to black carbon particles. Global Biogeochemical Cycles 19: GB1013.
Liang B , Lehmann J, Solomon D, Kinyangi J, Grossman J, O'Neill B, Skjemstad JO, Thies J, Luizão FJ, Petersen J and Neves EG 2006 Black carbon increases cation exchange capacity in soils. Soil Science Society of America Journal 70: 1719-1730.
Liang B ,Wang CH, Solomon D, Kinyangi J, Luizao F, Wirick S, Skjemstad J, Lehmann J 2013 Oxidation is Key for Black Carbon Surface Functionality and Nutrient Rentention in Amazon Anthrosols. British Journal of Environment & Climate Change 3 (1): 9-23.

 
 
Soil organic matter properties of Amazonian Dark Earths
Laboratory Experiments, since 2003:
High black carbon contents have been identified as the most important property of Amazonian Dark Earths that influence C dynamics in these soils. We conduct incubation experiments to study the C dynamics as well as changes in C fluxes in different soil C pools. NEXAFS (Near Edge X-ray Absorption Spectroscopy) using synchrotron radiation is used to obtain information about the surface properties of black C particles that are only 5-10 micrometer large, and about the macromolecular structure of Amazonian Dark Earths and its implication for carbon stability.
Publications:
Solomon D, Lehmann J, Thies J, Schäfer T, Liang B, Kinyangi J, Neves E, Petersen J, Luizão F and Skjemstad J 2007 Molecular signature and sources of biochemical recalcitrance of organic C in Amazonian Dark Earths. Geochimica et Cosmochimica Acta 71, 2285-2298.
Liang B, Lehmann J, Solomon D, Sohi S, Thies JE, Skjemstad JO, Luizão FJ, Engelhard MH, Neves EG and Wirick S 2008 Stability of biomass-derived black carbon in soils. Geochimica et Cosmochimica Acta 72, 6096-6078.
Liang B, Lehmann J, Sohi SP, Thies JE, O’Neill B, Trujillo L, Gaunt J, Solomon D, Grossman J, Neves EG and Luizão FJ 2010 Black carbon affects the cycling of non-black carbon in soil. Organic Geochemistry 41: 206–213.
Mao JD, Johnson RL, Lehmann J, Olk DC, Neves EG, Thompson ML, Schmidt-Rohr K 2012 Abundant and Stable Char Residues in Soils: Implications for Soil Fertility and Carbon Sequestration. Environmental Science & Technology 46: 9571-9576.
 
Field Experiments, since 2003:
The effect of black carbon on carbon cycling is quantified in forests on Amazonian Dark Earths in comparison to adjacent soils. (These experiments are conducted by Lucerina Truijillo and Gyovanne Ribeiro under the supervision of Flavio Luizao, INPA, Manaus)

For information about our research on biochar, please visit here.
 
 
Crop production and weed dynamics on Amazonian Dark Earths
Field Experiments Manaus, Brazil, 2002-2004:
This is the first field-scale experiment to quantify crop production on Amazonian Dark Earths in comparison to adjacent soils. Maize yield in weeded plots was as much as 63 times greater on Amazoniand Dark Earths (0.55 t/ha) than on corresponding adjacent soils (0 t/ha) without fertilizer additions, and location averages varied from 0 to 3.15 t/ha for Amazonian Dark Earths. The average percentage ground cover of weeds in weedy plots was up to 45 times greater on Amazonian Dark Earths (65–99%) than on corresponding adjacent soils (2–89%), and species richness was up to 11 times greater on Amazonian Dark Earths (4–14 species) than corresponding adjacent soils (1–8 species). The relative proportion of annual and leguminous weeds was 32 and 17% greater, respectively, on Amazonian Dark Earths than adjacent soils, and vegetative sprouting of plants was more common on sites that had been used less intensively in the past. In general, a similar weed community was observed on the different Amazonian Dark Earth sites, including many species typically associated with environments that have been highly disturbed by human activities.
Publications:
Major J, DiTommaso A, Lehmann J and Falcão NPS 2005 Weed dynamics on Amazonian Dark Earth and adjacent soils of Brazil. Agriculture, Ecosystems and Environment 111: 1-12.
 
 
Nutrient leaching and nutrient availability in Amazonian Dark Earths
Greenhouse Experiments Manaus, Brazil, 2000-2001:
Greenhouse experiments were conducted with rice and cowpea using closed and open systems (allowing the determination of leaching) at the Embrapa Amazonia Ocidental, Manaus, Brazil. (Collaborator: Jose Pereira da Silva Jr.)

Soil fertility and leaching losses of nutrients were compared between an Amazonian Dark Earth (Terra Preta) and a Xanthic Ferralsol from Central Amazônia. In the first experiment, cowpea (Vigna unguiculata (L.) Walp.) was planted in pots, while in the second experiment lysimeters were used to quantify water and nutrient leaching from soil cropped to rice (Oryza sativa L.). The Dark Earth showed significantly higher P, Ca, Mn, and Zn availability than the Ferralsol increasing biomass production of both cowpea and rice by 38-45 % without fertilization (P<0.05). The soil N contents were also higher in the Dark Earth but the wide C-to-N ratios due to high soil C contents led to lower foliar N contents of the crops. Despite the generally high nutrient availability, nutrient leaching was minimal in the Dark Earth, providing an explanation for their sustainable fertility. However, when inorganic nutrients were applied to the Dark Earth, nutrient leaching exceeded the one found in the fertilized Ferralsol.
African Dark Earths
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